# Use adaptive navigation containers instead of custom ones

> NavigationSplitView, UISplitViewController, TabView and UITabBarController adapt across every iPhone Duo pose with no pose-specific code.

Source: https://iphoneduosupport.com/checklist/adaptive-navigation-containers/

Severity: major
Category: navigation
Applies to: swiftui, uikit
Symptom: A hand-rolled navigation container that has to be taught about each pose, and gets one of them wrong.
Sources: https://developer.apple.com/videos/play/tech-talks/111461/
Last verified: 2026-09-09

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Apple lists these containers as fully adaptive across all poses:

- `NavigationSplitView` / `UISplitViewController`
- `TabView` / `UITabBarController`

Columns collapse when the device is closed, and tile or overlay when it is open. Sheets, popovers, context menus, and alerts adapt automatically too.

## Why this is worth the migration

A custom navigation container written for a single-screen iPhone now has to handle: two displays with different size classes, four or more poses, Split View multitasking at arbitrary widths, and a hinge that appears and disappears. That is a large matrix to get right and to keep right.

The system containers already handle it, and will handle whatever ships next. If you have been carrying a custom container for historical reasons, this is the strongest argument in years for retiring it.

```swift
NavigationSplitView {
    SidebarView()
} detail: {
    DetailView()
}
```

## The sidebar is the point

The inner display is regular-width and Apple specifically notes it leaves **room for sidebars**. An app that already has an iPad layout can usually reuse it directly; an iPhone-only app gets a genuinely better layout for the first time here.

## Presentation still adapts

You do not need to change how you present sheets, popovers, alerts, or context menus — those adapt on their own. The work is in the container, not the presentation.

## How to verify

Navigate your primary flows in every pose and on both displays. Any place you have written `if folded` or `if width >` inside navigation code is a candidate for deletion.

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Published by iPhone Duo Support (https://iphoneduosupport.com). Not affiliated with Apple Inc.